Cell Growth and Reproduction

All cells have a plasma membrane.◦ Controls what gets in and out.◦ Made of phospholipid molecules

All cells have cytoplasm◦ Gel-like substance

All cells have genetic material◦ Either DNA or RNA

All cells have ribosomes◦ For making proteins

What do all cells have in common?

Prokaryotic cells◦ Smallest cells◦ No nucleus or membrane-bound organelles◦ Examples: Bacteria

Eukaryotic cells◦ Complex cells◦ Have a nucleus and membrane-bound organelles◦ Examples: Plant cells and Animal Cells

Basic Cell Types

Most cells reproduce by dividing in two. Before they can do this, they must copy all

their genetic information, so that each new daughter cell has a full set of genetic material

The genetic material in eukaryotic cells is in the form of chromosomes.

Genetic Material

Humans have 46 chromosomes in the nucleus of every cell ◦ Two are the sex chromosomes (X and Y)

XX = female XY = male

◦ The other 44 are called autosomes◦ They occur in matching pairs

Called homologous chromosome pairs One chromosome in each pair comes from mom and

the other comes from dad

Cells grow and reproduce just like every other living thing.

The cell cycle represents the life cycle of a typical eukaryotic cell.

Cells Grow and Reproduce

G1 phase: Cell grows S phase: (synthesis) Cell copies its DNA G2 phase: Cell continues to grow and get

ready to divide Mitosis: The cell divides the content of the

nucleus Cytokinesis: The cell divides its cytoplasm

The G1, S, and G2 phase make up a stage called interphase. The cell spends most of its time in interphase.

The cell grows and copies DNA during interphase.

Interphase

Mitosis is when the cell divides the contents of the nucleus

Mitosis occurs in stages:◦ Prophase◦ Metaphase◦ Anaphase◦ Telophase

Mitosis

Cytokinesis occurs when the rest of the cell divides. ◦ For animal cells---the cell membrane pinches in

and the cell splits in two.◦ For plant cells---an new cell plate forms to create

a cell wall between the dividing cells.

Cytokinesis

Prokaryotes (bacteria cells) reproduce by a process known as Binary Fission.◦ DNA is circular (no

chromosomes)◦ DNA copies itself◦ Cell divides…

simple

Cell Reproduction in Bacteria Cells

The reproductive cells divide by a different method….Meiosis.

The cell divides twice. The result is four gamete cells (sperm and

egg cells) with half the number of chromosomes.

Meiosis

Fertilization—union of sperm and egg cell.

Sexual reproduction, involving the production of sperm and egg cells by meiosis followed by fertilization, ensures genetic variation in all offspring

Fertilization